What visual effect is caused by the edge gradient effect on an image?

The edge gradient effect is primarily responsible for creating smooth transitions in brightness levels at the edges of different objects within an image. This effect allows for a more natural appearance by blending colors and tonal values, which can be interpreted as streaking and shading. When edges have a gradient effect, they do not have harsh transitions but rather experience a softening that makes the adjacent colors and shades seamlessly merge. This blending can create an illusion of depth and dimension, enhancing the overall aesthetic of the image.

While the other options describe various visual artifacts that can occur in imaging, they do not specifically highlight the smooth gradation associated with the edge gradient effect. Fading and blurring relate more to overall image quality loss; noise and interference pertain to unwanted disruptions in the image, and contrast and brightness changes address overall tonal adjustments rather than the smooth transitions created by edge gradients.